Ruf der Erde is one of the finest and rare examples of Georg Kolbe's œuvre. Executed with the utmost sensibility for form and content, the artist brilliantly renders the figure's exceptional posture. The spirit with which Kolbe has depicted the model is highly evocative, elegantly capturing the figure's motion. The artist saw the human form as a vessel holding the greatest secret, which he sought to uncover. Commenting on his new development of style away from mere natural representation, Kolbe noted: 'My works no longer originate from nature...I have come closer to the plastic essence of things and can therefore lend more expression to the human form' (quoted in U. Berger, Op. Cit., p. 66, translated from German).

According to the expert Dr. Ursel Berger, Ruf der Erde is one of the last figures in the artist's œuvre portrayed 'in motion' before the artist departed on a new artistic endeavour, concentrating solely on still standing motifs. In its dramatic posture and arresting expression the sitter is filled with powerful expressive emotion, making the present work one of the most captivating bronzes in the artist's œuvre.

Ruf der Erde belongs to one of only four lifetime casts of this edition executed between 1933-1937. There are no posthumous casts of this model as the original plaster for the work was destroyed. The other three casts are housed in the Folkwang-Museum, Essen, the Georg-Kolbe-Museum, Berlin and the Rockefeller Collection.